Dividing attention within and between hemispheres: testing a multiple resources approach to limited-capacity information processing

Two experiments tested the limiting case of a multiple resources approach to resource allocation in information processing. In this framework, the left and right hemispheres are assumed to have separate, limited-capacity pools of undifferentiated resources that are not mutually accessible, so that tasks can overlap in their demand for these resources either completely, partially, or not at all. We tested all three degrees of overlap in demand for left hemisphere supplies, using dual-task methodology in which subjects were induced to pay different amounts of attention to each task. Experiment 1 compared complete and partial overlap by combining a verbal memory load with a task in which subjects named nonsense syllables briefly presented to either the left or right visual field (LVF and RVF, respectively). Experiment 2 compared complete versus no overlap by using the same verbal memory load combined with a laterally presented same-different judgment task that did not require a spoken response. Decrements from single-task performance were always more severe when the visual field task stimulus was presented to the RVF. Further, subjects in Experiment 1 were able to trade performance between tasks on both LVF and RVF trials because there was always at least some overlap in left hemisphere demand. In Experiment 2, performance trade-offs were observed on RVF (complete overlap) trials, but not on LVF trials, where no overlap in demand existed. These results contradict a single-capacity model, but they support the idea that the hemispheres' resource supplies are independent and have implications for both cerebral specialization and divided attention issues.     

Environmental demand and demand engendering behavior: an observational analysis of the type A pattern

In a prospective, observational study, we examined Type A behavior as a predictor of source of work demands, volume of work and nonwork activity, whether work begun was finished, and attention to more than one activity at a time. Police radio dispatchers (N = 72) were observed throughout one work shift, and half of the sample was observed on two additional work shifts. Behavioral categories showed substantial stability between observation occasions. Hierarchical regression revealed that two components of the broader Type A pattern, Hard-Driving Competitiveness and Job Involvement, were better predictors of work demands and behavior than was the global A score. Results support an interactional personality perspective in that Type As, relative to Type Bs, received more externally imposed demands from particular sources such as superiors or peers. However, these same Type As also generated more demand by simultaneously initiating work tasks for themselves and attending to multiple tasks.     

人在多项任务中的业绩及脑力负荷

在超脑力负荷状态下人的业绩是如何变化的？在实验中,让被试者同时完成四项内容不同的任务,即补偿追踪,选择反应,模拟雷达观察和算术运算。脑力负荷的强度是由改变工作的快慢节奏来实现的。实验的数据表明,随着脑力负荷的增加,人的业绩是逐渐下降的。在面对超负荷的多项任务时,人的信息处理过程更像一个单通道系统,集中精力完成某一工作,然后迅速地转移到下一个工作。     

Interaction effects among multiple job demands: an examination of healthcare workers across different contexts

Background and Objectives: Simultaneous exposure to time, cognitive, and emotional demands is a feature of the work environment for healthcare workers, yet effects of these common stressors in combination are not well established. Design: Survey data were collected from 125 hospital employees (Sample 1, Study 1), 93 ambulance service employees (Sample 2, Study 1), and 380 aged care/disability workers (Study 2). Methods: Hierarchical multiple regressions were conducted. Results: In Sample 1, high cognitive demand exacerbated high emotional demand on psychological strain and job burnout, whereas the negative effect of high emotional demand was not present at low cognitive demand. In Sample 2, a similar pattern between emotional demand and time demand on stress-remedial intentions was observed. In Study 2, emotional demand?×?time demand and time demand?×?cognitive demand interactions again revealed that high levels of two demands were stress-exacerbating and low levels of one demand neutralized the other. A three-way interaction on job satisfaction showed the negative impact of emotional demand was exacerbated when both time and cognitive demands were high, creating a “triple disadvantage” of job demands. Conclusions: The results demonstrate that reducing some job demands helps attenuate the stressful effects of other job demands on different employee outcomes.     

The interruptive effect of pain on attention

Pain is known to disrupt attentional performance in both healthy adults and patients with chronic pain. Exactly which aspects of attentional function are affected are, however, still to be determined. The primary aim of this investigation was to systematically examine the effects of experimentally induced pain on a range of attentional performance tasks. Following a review of tests of attentional disruption, seven best candidate tasks were selected and examined across seven experiments. The tasks were: continuous performance, flanker, endogenous precueing, n-back, inhibition, attentional switching, and divided attention. Healthy adult participants performed each of these tasks under three different conditions: a painful heat sensation, a warm heat sensation, and a nonheat control. Pain differentially affected attentional performance across these tasks; pain-related attentional impairment was found on the n-back, attentional switching, and divided attention tasks, but not on the other tasks. This finding suggests that the aspects of attention most affected by pain are those essential for the completion of complex tasks that require the processing of multiple cues and control over attentional deployment. These results are discussed in the context of an emerging view of pain as a demand for executive control and the development of measures that could be used to examine attentional disruption in the context of pain.     

The interruptive effect of pain on attention

Pain is known to disrupt attentional performance in both healthy adults and patients with chronic pain. Exactly which aspects of attentional function are affected are, however, still to be determined. The primary aim of this investigation was to systematically examine the effects of experimentally induced pain on a range of attentional performance tasks. Following a review of tests of attentional disruption, seven best candidate tasks were selected and examined across seven experiments. The tasks were: continuous performance, flanker, endogenous precueing, n-back, inhibition, attentional switching, and divided attention. Healthy adult participants performed each of these tasks under three different conditions: a painful heat sensation, a warm heat sensation, and a nonheat control. Pain differentially affected attentional performance across these tasks; pain-related attentional impairment was found on the n-back, attentional switching, and divided attention tasks, but not on the other tasks. This finding suggests that the aspects of attention most affected by pain are those essential for the completion of complex tasks that require the processing of multiple cues and control over attentional deployment. These results are discussed in the context of an emerging view of pain as a demand for executive control and the development of measures that could be used to examine attentional disruption in the context of pain.     

Different effects of dual task demands on the speech of young and older adults

Young and older adults provided language samples in response to elicitation questions while concurrently performing 3 different tasks. The language samples were scored on three dimensions: fluency, grammatical complexity, and content. Previous research had suggested the hypothesis that the restricted speech register of older adults is buffered from the costs of dual task demands. This hypothesis was tested by comparing language samples collected during a baseline condition with those produced while the participants were performing the concurrent tasks. The results indicate that young and older adults adopt different strategies when confronted with dual task demands. Young adults shift to a restricted speech register when confronted with dual task demands. Older adults, who were already using a restricted speech register, became less fluent although the grammatical complexity and informational content of their speech was preserved. Hence, some but not all aspects of older adults' speech are buffered from dual task demands.     

Tracking multiple targets with multifocal attention

Attention allows us to monitor objects or regions of visual space and select information from them for report or storage. Classical theories of attention assumed a single focus of selection but many everyday activities, such as video games, navigating busy intersections, or watching over children at a swimming pool, require attention to multiple regions of interest. Laboratory tracking tasks have indeed demonstrated the ability to track four or more targets simultaneously. Although the mechanisms by which attention maintains contact with several targets are not yet established, recent studies have identified several characteristics of the tracking process, including properties defining a 'trackable' target, the maximum number of targets that can be tracked, and the hemifield independence of the tracking process. This research also has implications for computer vision, where there is a growing demand for multiple-object tracking.     

Spatial offloading in multiple task monitoring

Coordinating multiple tasks requires a high degree of cognitive control, and individuals with limited executive functions often show difficulties in everyday multitasking. We tested the hypothesis that demands on executive control can be alleviated by internally representing the temporal pattern of goals and deadlines as spatial relations. In two experiments, participants completed a multitasking session by monitoring deadlines of four clocks running at different rates, along with separate tasks of executive functioning and spatial ability. In Experiment 1, individual and gender-related differences in spatial ability (mental rotation) predicted multitasking performance, beyond the contributions of both the updating and inhibition components of executive functioning, and even when spatial cues were eliminated from the layout of the monitoring task. Experiment 2 extended these findings by showing that concurrent spatial load impaired task monitoring accuracy, and that these detrimental effects were accentuated when spatial abilities were compromized due to fluctuation in female sex hormones. These findings suggest that multiple task monitoring involves working memory-related functions, but that these cognitive control demands can be offloaded by relying on spatial relation processes.     

Evidence for the Involvement of the Rat Prefrontal Cortex in Sustained Attention

Previous studies suggest that, in both humans and rats, the prefrontal cortex (PFC) is involved in both selective and divided attention. We have also shown that the PFC is involved in response selection and that its involvement is modulated by the cognitive effort required by the task. However, the role of the PFC is much less clear when no response selection is required. The purpose of the present experiments was to assess the role of the PFC in attentional functions with a low response-selection demand. We used two tasks in which information processing was effortful but where the demand on a response selection process is low. Moreover, we assessed two different types of visual attentional functions: selective attention (Experiment 1) and sustained attention (Experiment 2). The results showed a differential involvement of the PFC in the two tasks. Selective attention was not impaired by prefrontal lesions when the number of possible positions for the stimulus on which the subjects must focus was restricted to two (Experiment 1). In contrast, prefrontal rats were unable to sustain their attention long enough to detect, and react to, subtle variations in brightness (Experiment 2). This result suggests a dissociation between different types of attentional functions depending upon the integrity of the PFC. More specifically, results in Experiment 2 suggest an involvement of the PFC in sustained attention. Finally, the overall results show that even in tasks involving low demands on response selection the PFC is involved in attentional functions.     

ASSESSING THE UTILITY OF A DEMAND ASSESSMENT FOR FUNCTIONAL ANALYSIS

We evaluated the utility of an assessment for identifying tasks for the functional analysis demand condition with 4 individuals who had been diagnosed with autism. During the demand assessment, a therapist presented a variety of tasks, and observers measured problem behavior and compliance to identify demands associated with low levels of compliance or high levels of problem behavior (low‐probability demands) and demands associated with high levels of compliance or low levels of problem behavior (high‐probability demands). Results showed that clearer functional analysis outcomes were obtained for 3 of the 4 participants when low‐probability rather than high‐probability demands were used.     

Different Effects of Dual Task Demands on the Speech of Young and Older Adults

Abstract

Young and older adults provided language samples in response to elicitation questions while concurrently performing 3 different tasks. The language samples were scored on three dimensions: fluency, grammatical complexity, and content. Previous research has shown that older adults use a restricted speech register that is grammatically less complex than young adults’ and has suggested that this restricted speech register is buffered from the costs of dual task demands. This hypothesis was tested by comparing language samples collected during a baseline condition with those produced while the participants were performing the concurrent tasks. The results indicate that young and older adults adopt different strategies when confronted with dual task demands. Young adults shift to a restricted speech register when confronted with dual task demands. Older adults, who were already using a restricted speech register, became less fluent although the grammatical complexity and informational content of their speech was preserved. Hence, some but not all aspects of older adults’ speech are buffered from dual task demands.     

In vivo functional assessment and multi-element interventions for problem behaviors of students with disabilities in classroom settings

Persons with developmental disabilities often do not follow instructions or complete tasks in educational settings, thus further disadvantaging themselves as they try to lead more normalized lives. The purpose of this paper was to address the problems of three persons referred for not following instructions and for engaging in associated behavior problems (e.g., crying, hitting, throwing materials) when given instructions. A functional assessment was conducted in the natural school setting without any prescribed conditions as in analogue functional assessments. Results of the assessments showed that problem behaviors for two subjects occurred much more in demand conditions requiring active responses than in demand conditions requiring passive responses. The results for a third subject showed problem behaviors were associated with toileting demands, less so with other demand conditions, but not with conditions in which there were an absence of demands. Individualized multi-element interventions were based on the negative reinforcement hypothesis and were intended to make tasks less aversive and to make instructions easier to understand. Results of the interventions showed increases in task engagement and decreases in problem behaviors during the active tasks and toileting tasks for which interventions were programmed, as well as for the passive tasks and other demand conditions for which no interventions were programmed. Results were discussed in terms of the value of functional assessments in directing therapists to base interventions on hypotheses of the function of the presenting problem.     

Attentional resource demands of visual word recognition in naming and lexical decisions.

Attentional demands of lexical access were assessed with dual-task methodology. Subjects performed an auditory probe task alone (single-task) or combined (dual-task) with either a lexical decision or a naming task. In Experiment 1, probe performance showed a decrement from single- to dual-task conditions during recognition of words in both lexical decision and naming tasks. In addition, decrements in probe performance were larger during processing of low-frequency compared with high-frequency words in both of the word recognition tasks. Experiment 2 showed that the time course of frequency-sensitive demands was similar across lexical decision and naming tasks and that attention is required early in the word recognition sequence. The results support the assumption that lexical access is both frequency sensitive and attention demanding.     

Target enhancement and distractor inhibition affect transitory surround suppression in dual tasks using multiple rapid serial visual presentation streams

Few studies have investigated the interaction between temporal and spatial dimensions on selective attention using dual tasks in the multiple rapid serial visual presentation (RSVP) paradigm. A phenomenon that the surround suppression in space changes over time (termed transitory surround suppression, TSS, in the present study) has been observed, suggesting the existence of this time–space interaction. However, it is still unclear whether target enhancement or distractor inhibition modulates TSS. Four behavioural experiments were conducted to investigate the mechanism of TSS by manipulating the temporal lag and spatial distance factors between two targets embedded in six RSVP streams. The TSS effect was replicated in a study that eliminated confounds of perceptual effects and attentional switch (Experiment 1). However, the TSS disappeared when two targets shared the same colour in a between-subjects design (Experiment 2a) and a within-subject design (Experiment 2b), suggesting the impact of target enhancement on TSS. Moreover, the TSS was larger for within-category than for between-category distractors (Experiment 3), indicating the impact of distractor inhibition on TSS. These two influences on TSS under different processing demands of target and distractor processing were further confirmed in a skeletal design (Experiment 4). Overall, combinative effects of target enhancement and distractor suppression contribute to the mechanisms of time–space interaction in selective attention during visual search.     

Studies of the side effect profile of clozapine

All patients treated at the County Hospital for Neurology and Psychiatry in Ueckermuende from 1981 to 1984 with Klopazin were included in a critical analysis of the side effects of the drug, paying special attention to those reported in the literature. Besides the symptoms already identified, delirium and hypotonic circulation dysregulation are receiving increased clinical attention, which indicates that special care methods are called for.     

Chimpanzee (Pan troglodytes) handedness: variability across multiple measures of hand use

This study examined intertask consistency in handedness across multiple measures of hand use in a sample of 187 chimpanzees (Pan troglodytes). Hand preferences for 2 to 6 measures were collected from the sample, and hand preference scores were derived on the basis of the individual hand preferences for each measure. Seven of 15 possible intratask correlations were significant, with some degree of clustering depending on the motor demands of the tasks. Two overall measures of handedness revealed population-level right-handedness in the chimpanzees, although the degree of bias was reduced for chimpanzees tested on more than 3 measures of hand use. The results are interpreted in the context of several recent studies that proposed theoretical models of handedness in nonhuman primates.     

Evidence for processing stages in skill acquisition: a dual-task study

We investigated the changes of resource demand during the acquisition of a sensorimotor skill, namely the tracking of a visual target under reversed visual feedback. This acquisition task was performed alone or concurrently with one of four manual reaction-time tasks as loading tasks, designed to tap different computational resources. As expected, we found tracking performance to deteriorate upon vision reversal and then to gradually improve with practice. We further found that acquisition task and loading task interfered little before vision reversal but substantially afterwards. Most importantly, we observed a different time-course of interference for each of our four loading tasks. The particular pattern led us to conclude that resources related to spatial attention and sensory transformations are in highest demand early during skill acquisition and those pertinent to movement preparation somewhat later. Our findings thus provide experimental support for the theory that motor learning progresses in stages characterized by different resource requirements.     

The Development of Attention and Its Relations to Language in Infancy and Toddlerhood

We investigated longitudinally the development of attention in two free-play tasks and the relation between attention in those tasks and language ability in toddlerhood. We observed developmental differences in attention from 9 and 31 months both as children investigated a single object and as they investigated multiple objects. Attention in these contexts at 9 months was differentially related to vocabulary at 31 months, but concurrent measures of attention at 31 months were not related to vocabulary at that age. The results are discussed in terms of the potential processes guiding the relation between attention and cognitive outcome and the development of endogenous control of attention.     

Listening to polyphonic music recruits domain-general attention and working memory circuits

Polyphonic music combines multiple auditory streams to create complex auditory scenes, thus providing a tool for investigating the neural mechanisms that orient attention in natural auditory contexts. Across two fMRI experiments, we varied stimuli and task demands in order to identify the cortical areas that are activated during attentive listening to real music. In individual experiments and in a conjunction analysis of the two experiments, we found bilateral blood oxygen level dependent (BOLD) signal increases in temporal (the superior temporal gyrus), parietal (the intraparietal sulcus), and frontal (the precentral sulcus, the inferior frontal sulcus and gyrus, and the frontal operculum) areas during selective and global listening, as compared with passive rest without musical stimulation. Direct comparisons of the listening conditions showed significant differences between attending to single timbres (instruments) and attending across multiple instruments, although the patterns that were observed depended on the relative demands of the tasks being compared. The overall pattern of BOLD signal increases indicated that attentive listening to music recruits neural circuits underlying multiple forms of working memory, attention, semantic processing, target detection, and motor imagery. Thus, attentive listening to music appears to be enabled by areas that serve general functions, rather than by music-specific cortical modules.